1. Field of the Invention
This invention relates generally to the cutting of elongated tubular material into short individual tube sections. More specifically, the invention relates to an apparatus for simultaneously making a plurality of circumferential cuts incompletely through the wall of a rubber tube or the like mounted on a rotating mandrel. The depths of the cuts are predetermined to result in the retention of thin, frangible, residual tube wall portions at the locations of the cuts. The residual wall portions are of constant thickness and may be reproduced in subsequently cut tubes which may be of varying thickness with no adjustment of the device being required.
2. Description of the Prior Art
Various devices have been proposed in the past for cutting elongated tubular material into individual shorter sections. It has been found in the past, however, that in such a cutting operation, it is desirable when cutting tubular material which is mounted on a rotating mandrel, to keep the cutting knives from contacting the mandrel, so that it would not become scored by the knives, and so that the knives would not become dull.
U.S. Pat. No. 3,143,041 discloses a means for preventing the damage of the edge of a rotary cutter in such an operation and proposes the use of a cutting platen equipped with an insert of fiber or similar material at its outer periphery opposite the rotary cutter. The insert is of a hardness appreciably less than metal and minimizes damage to the edge of the rotary cutter upon penetration thereof. A cut depth limit roller mounted on the knife support and engaging the outer surface of the tubular material being cut is also provided.
U.S. Pat. No. 1,033,411 proposes a solution to the problem of eliminating undue movement of a plurality of cutters relative to the material supporting roll during operation of the machine. This patent discloses the use of an adjustable means for locking or securing the cutter bar against undue movement in its bearings when the cutters are in operative position. The adjustable means comprises a friction locking device carried in each of a pair of spaced posts on each side of the machine, thus maintaining the accuracy of the cutters in their adjusted cutting position relative to the opposing bed roll during working operation.
U.S. Pat. No. 3,207,016 discloses a device for cutting sheet material such as roofing so that it can later be broken into a plurality of individual shingles. The circular knife in this device is held in constant spaced relation to a flat, horizontal material-supporting surface by means of rollers mounted on the ends of the knife-carrying shaft and which ride in inwardly opening channels which extend longitudinally of the table as part of the frame. Thus, a relatively constant spacing is achieved between the knife and the material-supporting surface.
Another arrangement for controlling and limiting the depth of penetration of rotary knives into the surface of a cylindrical object is disclosed by U.S. Pat. No. 2,314,102. In this device either an adjustable shoe or rollers may be provided to ride on the outer surface of the object while rotatable knives mounted on the apparatus score or cut into the surface to a predetermined depth. Adjustable means is provided to control and limit the depth of penetration of the rotary knives.
An apparatus for scoring or cutting paper is disclosed by U.S. Pat. No. 246,923. The apparatus includes a series of pressure rolls and rotary disc cutters. Each of the rolls and cutters are individually adjustably mounted on a supporting bar extending transversely across the machine to permit varying of the relationship of the rolls and cutters with respect to a bed roll over which the paper to be cut is passed.
The prior art, however, discloses no solution to the problem of circumferentially cutting an elongated rubber tube incompletely through the thickness of the wall surface thereof in such a manner that very thin, frangible residual wall portions of precise, constant thickness remain at the location of the cuts, thereby enabling the tube to be removed from its supporting mandrel in one piece and broken later, if desired, into individual short sections by hand or machine.